Perforation modes of double-layered plates with air space struck by a blunt rigid projectile

In the cases of the perforation of a single-layered metal plate struck by a blunt rigid projectile, along with the increase of the plate thickness and that of the projectile velocity, the failure mode of the metal plate may transform from shear plugging to adiabatic shear plugging. Therefore, regarding the perforation of double-layered or multi-layered plates, the failure modes of various plates can be quite different. In this work we investigated these different perforation modes by conducting experimental analyses on the perforations of single- and double-layered Weldox E steel plates with air space. Our results indicate that, in the case of a higher initial striking velocity, the failure mode of the first layer plate is adiabatic shear plugging, while that of the second layer plate is adiabatic shear plugging or shear plugging as the striking velocity of the projectile slows down. We conclude that the final failure mode of the double-layered plates is the mixture of both shear plugging and adiabatic shear plugging.